EQUISETUM. 255 
been meet with only in a limited number of localities in 
Ireland, Scotland, and the north of England. 
Equisetum arvense, Linneeus. 
The Corn-field Horsetail. 
This is the most common of the species, and in many 
places is an injurious weed, very difficult to eradicate. It 
occurs here and there, almost everywhere, in fields and 
waste places, especially where the soil is inclined to be 
sandy, and more abundant in moist than in dry places. It 
has long, creeping, underground stems, which are a good 
deal branched, and are cylindrical and jointed in the same 
way as the stems which rise above-ground. At the joints 
they throw out whorls of tough, branching, fibrous roots. 
The aerial stems are of two kinds, the one simple and 
bearing the fructification only, the other branched and 
perfectly barren. 
The fertile stems are quite without branches, and grow 
up early in spring, arriving at maturity and perishing 
long before the barren ones have completed their growth. 
They reach maturity in April and May. The stems vary 
from three to eight or ten inches in height. They are 
hollow, succulent when fresh, and of a light brown colour, 
